(NBC NEWS) -- A forensic pathologist testified Tuesday that George Zimmerman's account of what happened the night he fatally shot Trayvon Martin last year was "consistent" with the evidence he had seen from the crime scene.

Dr. Vincent Di Maio, a gunshot wound expert hired by the defense, said Zimmerman's gun's muzzle was two to four inches away from Martin's chest when it went off and was against Martin's clothing, which Di Maio says the evidence shows was hanging down from Martin's body.

"This is consistent with Mr. Zimmerman's account that Mr. Martin was over him, leaning forward at the time he was shot," Di Maio told the court. Di Maio has written four books, including one called "Gunshot Wounds: Practical Aspects of Firearms, Ballistics, and Forensics Techniques."

When asked by defense attorney Don West if the gunshot wound was shot at a 90-degree angle to the body, Di Maio said, "It does not appear so."

The testimony is considered crucial for the defense, which is arguing that Zimmerman, 29, shot Martin, 17, out of self-defense when the unarmed teen attacked him in a gated community in Sanford, Fla., on Feb. 26, 2012. Zimmerman has pleaded not guilty to charges of second-degree murder in Martin's death.

Di Maio - who was questioned about the mechanics of gunfire and described himself as having a "very strong interest in gunshot wounds" - also said "powder tattoo marks," marks on skin caused by a gun fired at close range, further supported Zimmerman's account.

"The medical evidence, the gunshot wound, the tattooing, is consistent with his statement," he said.

"The most important point is the nature of the defect in the clothing and the powder tattooing," he added, referring to the bullet hole in Martin's clothes and the marks on his chest. "If you lean over somebody, you will notice that the clothing tends to fall away from the chest. If instead you're lying on your back and somebody shoots you, the clothing is going to be against your chest. So that the fact that we know the clothing was 2 to 4 inches away is consistent with somebody leaning over the person doing the shooting, and that the clothing is 2 to 4 inches away from the person firing."

Under cross-examination, Di Maio said Martin could have been pulling away from Zimmerman.

Di Maio also said that for at least 10 to 15 seconds after Martin sustained a gunshot wound, he would have been capable of retracting his arms due to the amount of oxygen left in his brain, another important testimony for the defense. Zimmerman has said that after the shooting he moved Martin's hands apart, but police have said Martin's body was discovered face-down in the grass, his hands underneath.

Later in the afternoon, O'Mara told the judge that the defense is "probably going to be done tomorrow."

Question over animation
The testimony followed a hearing earlier in the morning in which Judge Debra Nelson deferred a ruling on whether to allow an animation that illustrates what may have happened in the fatal confrontation between the neighborhood watch volunteer and Martin.

The animation, which according to defense attorney Mark O'Mara has been reduced to "more like a series of stills," originally included punches being thrown by Martin at Zimmerman. The punches have now been excluded.

In a continued push to get the animation presented to the jury - which prosecutors argue would be misleading - the defense brought in the crime scene and accident recreation animation graphic artist who was hired to reconstruct his version of the Martin-Zimmerman confrontation. Jurors were not in the courtroom during the hearing.

Daniel Schumaker of California-based Contrast Forensics said he uses a variety of pieces of software, equipment, robotic lasers that measure three-dimensional space, and "motion-capture" suits to recreate crime scenes and accidents.

"It's perfect for court because then you can - it gives you a running log of all the movements. Say, for example, somebody hits something and causes a certain amount of damage. With this suit, I can do that same action and from the accelerometers, you could see how much force it took to cause that amount of damage," Schumaker said.

"The engineers that have developed it, they not only use it for motion-capture like this, but it's used in biometrics, for physical rehabilitation and physical therapy," he said.

Schumaker was hired in April 2012 by the defense to do a recreation of their confrontation. He said he used coroner photos, police reports, audio from 911 calls, and witness statements for his recreation. He also flew from California to the crime scene to use a motion-capture suit on-site.

"There's a couple volunteers from your law office that put the suits on. Then as far as the timing, for the second part of the scenario where they were on the ground, I used the audio from the 911 call for the timing of it to time it with the shot of the gun," he said, referring to the moments before the gun went off when the two were on the ground fighting each other, according to witness accounts and Zimmerman's statement to police.

Prosecutors filed a motion last Friday to block the animation, arguing, among other objections, that it "artificially depicts lighting conditions" on the rainy night Zimmerman and Martin tussled and "relies in part upon statements in police reports, some of which were in fact contrary to testimony repeated by the same witness in court." They also object to the animation because it wasn't presented at any pretrial hearings.

Editor's note: George Zimmerman has sued NBC Universal for defamation. The company strongly denies the allegation.